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A046686
Numbers k such that k and sum of cubes of divisors of k are relatively prime.
3
1, 2, 3, 4, 5, 7, 8, 9, 11, 13, 16, 17, 19, 23, 25, 27, 29, 31, 32, 36, 37, 39, 41, 43, 47, 49, 50, 53, 55, 57, 59, 61, 63, 64, 65, 67, 71, 73, 75, 77, 79, 81, 83, 85, 89, 93, 97, 98, 100, 101, 103, 107, 109, 111, 113, 115, 117, 121, 125, 127, 128, 129, 131, 137, 139, 143
OFFSET
1,2
COMMENTS
All even terms are either squares or doubled squares. - Ivan Neretin, Dec 30 2015
The asymptotic density of this sequence is 0 (Dressler, 1974). - Amiram Eldar, Jul 23 2020
LINKS
Robert E. Dressler, On a theorem of Niven, Canadian Mathematical Bulletin, Vol. 17, No. 1 (1974), pp. 109-110.
MATHEMATICA
Select[Range[143], GCD[#, DivisorSigma[3, #]] == 1 &] (* Ivan Neretin, Dec 30 2015 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved